How to fix Wordpress Internal Server Error On Cloud ?

Hello all. I am Newbie here !
I lost Control of My Wordpress Account totally . after updating Module_rewrite of " WP Super Cache Plugin’s Advanced Tab ".I think , I got problem with my .htaccess after updating module_rewrite . Since then I see only " Internal Sever Error 500 " and can’t do nothing anymore .
I can’t even login to Admin Area and can’t access Dashboard anymore .
If I were hosting in Traditional Web Hosting , I know where is the root folder of Wordpress PlugIn and can control them .
But here in the Cloud , I lost all control of my site and don’t know what to do and where is Root Folder.
Can anyone help me how to fix this problem and my site up and running again .
And access to every wordpress files and folder to manage permission , etc,.
Any Help Would be so appreciated ! Please …
Thanks in advance .